1. Field of the Invention
The present invention relates to a graphic image drawing device, and more particularly to a graphic image drawing device capable of drawing two thick line segments intersecting at respective ends thereof with smooth lines at the intersecting portion.
2. Description of the Prior Art
Conventionally, a cathode ray tube (CRT), a laser beam printer or the like have been used as a graphic image drawing device. The device receives graphic data from a host computer and a graphic image is drawn upon converting the graphic data to bit map data or runlength data.
Given a width w of a line and the coordinates of two points a and b defining a length of the line as shown in FIG. 1, the coordinates of four points a0, a1, a2 and a3 defining a thick line segment can be computed. Based on the data thus computed, bit map data or runlength data representative of the thick line segment are obtained for a graphical processing.
However, when two intersecting lines are to be depicted, a problem arises in how the intersecting portion of the two line segments are to be depicted. Specifically, when two thick line segments A and B are drawn to intersect at respective ends thereof as shown in FIG. 2, the portion around the merging point C of the two line segments A and B is seen to be somewhat incomplete. Such portion is notable as the line becomes thicker.